Where an image of a document is to be converted into an electrical video signal which in turn is to be formed into a digital signal for storage purposes, it is important that the image which is to be scanned and converted into the signal is itself in sharp focus. Failure to ensure this will mean an inferior conversion and inferior video signal and inaccurate digital signal. In turn this will result in an inferior if not useless reproduction of the original document upon reconstruction of the video signal in a television display.